Harem Link Cultivation System - Chapter 13: The First Collapse

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

They call him Ghost.A name whispered in fear across warzones, black markets, and underworld circles.To the world, he's a phantom—a faceless mercenary who leaves no trace but bodies in his wake.To his enemies, he’s a death sentence.To his brothers-in-arms in Graveyard, he’s family.But to himself... he's a haunted man searching for a past stolen in gunfire and smoke.After a flawless mission deep in the Eastern Province, Ghost returns to the hidden forest base he's called home for sixteen years. Yet the victory is short-lived. His foster father, the commander delivers an unexpected order:“That was your last mission.”Now, Ghost—real name Miles Sterling—must step out of the shadows of war and into a world he’s never known. Guided only by a scarred letter, a fading memory, and the voice of a woman he hasn’t seen since the day everything was taken from him.But war forged more than his body and name.Behind the mask, behind the scars, Miles has another secret.One he’s kept hidden even from his brothers in arms.He’s not just a weapon.He’s a ghost with a fortune—a hidden empire he built in silence, across borders and black markets, forged in strategy and blood.A man of many names, and many shadows.Beneath the bullets, tattoos, and silence lies a truth buried in ashes.And Ghost is about to dig it up—one letter, one enemy, one memory at a time.

Lin Fan acquired the Sign-in System that led him on the path of the life of a god-level nouveau riche.

Lucien is an exploited employee, with a miserable salary and a life marked by loneliness... as well as carrying a secret that beats within him: the mysterious Black Blood.One night, on his way home, he is attacked by vampires. What seemed like the end becomes the beginning of an unexpected destiny.Lucien wakes up as a vampire... And not just any one.Amidst intrigue, power, and an unexpected marriage to beautiful vampires, he will be drawn into the dangerous supernatural world.What Lucien never imagined was that this strange condition he detested so much would be the key to transforming him into the most feared... and powerful vampire of all time....So, about the NTR stuff. Netorare? Absolutely not. Netori? I'll leave that up to fate... Oh, I almost forgot, there will be no incest in this novel.